U.S. patent application number 13/515705 was filed with the patent office on 2012-11-08 for method for transceiving channel information, and terminal and base station using same.
This patent application is currently assigned to Pantech Co., Ltd.. Invention is credited to Sungkwon Hong, Kibum Kwon, Kyoungmin Park, Sungjin Suh.
Application Number | 20120281578 13/515705 |
Document ID | / |
Family ID | 44401008 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120281578 |
Kind Code |
A1 |
Hong; Sungkwon ; et
al. |
November 8, 2012 |
METHOD FOR TRANSCEIVING CHANNEL INFORMATION, AND TERMINAL AND BASE
STATION USING SAME
Abstract
The present description relates to a wireless communication
system and to a method for transceiving channel information through
carrier aggregation, and a terminal and a base station using the
method. The method described in the present description comprises:
receiving channel information from a user terminal, and generating
a sub-band group from one or more subbands contained in at least
one or more component carriers; and receiving, from the user
terminal, channel information for each of the sub-band groups
through a control channel.
Inventors: |
Hong; Sungkwon; (Seoul,
KR) ; Kwon; Kibum; (Ansan-si, KR) ; Park;
Kyoungmin; (Goyang-si, KR) ; Suh; Sungjin;
(Seoul, KR) |
Assignee: |
Pantech Co., Ltd.
Seoul
KR
|
Family ID: |
44401008 |
Appl. No.: |
13/515705 |
Filed: |
December 7, 2010 |
PCT Filed: |
December 7, 2010 |
PCT NO: |
PCT/KR2010/008685 |
371 Date: |
July 24, 2012 |
Current U.S.
Class: |
370/252 ;
370/329 |
Current CPC
Class: |
H04L 1/0026 20130101;
H04L 1/0029 20130101; H04L 5/001 20130101; H04W 24/10 20130101 |
Class at
Publication: |
370/252 ;
370/329 |
International
Class: |
H04W 24/10 20090101
H04W024/10; H04W 72/08 20090101 H04W072/08; H04W 72/06 20090101
H04W072/06; H04W 72/04 20090101 H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2009 |
KR |
10-2009-0124441 |
Dec 6, 2010 |
KR |
10-2010-0123233 |
Claims
1. A method for a base station (BS) to receive channel information
in a wireless communication system using at least one component
carrier (CC), the method comprising: receiving channel information
from a user equipment (UE); generating a subband group with respect
to one or more subbands included in the at least one CC, based on
the received channel information; transmitting information
associated with the generated subband group to the UE; and
receiving, from the UE through a control channel, group-based
channel information of each subband corresponding to the subband
group, wherein the subband group comprises at least one subband
having the same channel information; and wherein the information
associated with the subband group comprises a total number of
generated subband groups, subband group identification information
to be used for identifying each subband group, and subband
identification information to be used for identifying a subband
included in each subband group.
2. The method as claimed in claim 1, wherein the subband group
comprises one or more subbands included in a first CC and one or
more subbands included in a second CC; and the channel information
corresponds to information indicating a status of a downlink (DL)
channel of the subbands included in the subband group.
3. The method as claimed in claim 2, wherein at least one of the
first CC and the second CC does not include the control
channel.
4. The method as claimed in claim 1, wherein the control channel
corresponds to a physical downlink control channel (PUCCH).
5. The method as claimed in claim 1, wherein the channel
information includes at least one of channel quality indicator
(COI) information, a precoding matrix indicator (PMI), a rank
indicator (RI), information indicating a degree of noise of a
channel, information associated with an error occurring in a
channel, channel status information, and information associated
with measured quality of a channel.
6. The method as claimed in claim 1, further comprising: receiving
subband group updating request information from the UE; and
transmitting, to the UE, subband group updating information
including a list of updated subband groups, wherein the subband
group updating request information comprises a portion
corresponding to a generation code or a cancellation code
indicating that a subband group is newly generated or cancelled, a
portion indicating a total number of newly generated subband groups
or cancelled subband groups, and a portion indicating
identification information (number) to be used for identifying each
generated or cancelled subband group and a subband included in each
subband group.
7. A method for a user equipment (UE) to transmit channel
information in a wireless communication system that uses at least
one component carrier (CC), the method comprising: transmitting, to
a base station (BS), channel information associated with one or
more subbands included in the at least one CC; receiving, from the
BS, information associated with a subband group generated by
grouping the one or more subbands included in the at least one CC;
transmitting, to the BS through a control channel, group-based
channel information of each subband by using the channel
information associated with the one or more subbands as the
group-based channel information of each subband corresponding to
the subband group, wherein the subband group comprises at least one
subband having the same channel information; and wherein the
information associated with the subband group comprises a total
number of generated subband groups, subband group identification
information to be used for identifying each subband group, and
subband identification information used for identifying a subband
included in each subband group.
8. The method as claimed in claim 7, wherein the subband group
comprises one or more subbands included in a first CC and one or
more subbands included in a second CC; and the channel information
corresponds to information indicating a status of a downlink (DL)
channel of the subbands included in the subband group.
9. The method as claimed in claim 8, wherein at least one of the
first CC and the second CC does not include the control
channel.
10. The method as claimed in claim 7, wherein the control channel
corresponds to a physical downlink control channel (PUCCH).
11. The method as claimed in claim 7, wherein the channel
information comprises at least one of channel quality indicator
(COI) information, a precoding matrix indicator (PMI), a rank
indicator (RI), information indicating a degree of noise of a
channel, information associated with an error occurring in a
channel, channel status information, and information associated
with measured quality of a channel.
12. The method as claimed in claim 7, further comprising:
extracting a parameter to be used for updating a subband group,
based on subband-based channel information associated with each of
the at least one CC and subband group-based channel information;
and generating subband group updating request information when the
parameter exceeds a tolerance, and transmitting the subband group
updating request information to the BS, wherein the subband group
updating request information comprises a portion corresponding to a
generation code or a cancellation code indicating that a subband
group is newly generated or cancelled, a portion indicating a total
number of newly generated subband groups or cancelled subband
groups, and a portion indicating identification information
(number) to be used for identifying each generated or cancelled
subband group and a subband included in each subband group.
13. A wireless communication system, the system comprising: a
subband grouping management unit to generate a subband group with
respect to one or more subbands included in at least one component
carrier (CC), based on channel information received from a user
equipment (UE); and a transceiving unit to transmit subband
grouping information associated with the subband group to the UE,
and to receive group-based channel information of each subband
corresponding to the subband group through a control channel,
wherein the subband group comprises at least one subband having the
same channel information; and wherein the information associated
with the subband group comprises a total number of generated
subband groups, subband group identification information to be used
for identifying each subband group, and subband identification
information to be used for identifying a subband included in each
subband group.
14. The system as claimed in claim 13, wherein the subband group
comprises one or more subbands included in a first component
carrier (CC) and one or more subbands included in a second CC; and
the channel information corresponds to information indicating a
status of a downlink (DL) channel of the subbands included in the
subband group.
15. The system as claimed in claim 14, wherein at least one of the
first CC and the second CC does not include the control
channel.
16. The system as claimed in claim 13, wherein the control channel
corresponds to a physical downlink control channel (PUCCH).
17. The system as claimed in claim 13, wherein the channel
information comprises at least one of channel quality indicator
(COI) information, a precoding matrix indicator (PMI), a rank
indicator (RI), information indicating a degree of noise of a
channel, information associated with an error occurring in a
channel, channel status information, and information associated
with measured quality of a channel.
18. The system as claimed in claim 13, wherein, when the
transceiving unit receives subband group updating request
information from the UE, the subband grouping management unit
generates subband group updating information including a list of
updated subband groups, wherein the subband group updating request
information comprises a portion corresponding to a generation code
or a cancellation code indicating that a subband group is newly
generated or cancelled, a portion indicating a total number of
newly generated subband groups or cancelled subband groups, and a
portion indicating identification information (number) to be used
for identifying each generated or cancelled subband group and a
subband included in each subband group.
19. A user equipment (UE), the UE comprising: a receiving unit to
receive, from a base station (BS), subband grouping information
associated with a subband group generated by grouping one or more
subbands included in at least one component carrier (CC); a subband
channel information measuring unit to measure channel information
associated with the one or more subbands included in the at least
one CC; a subband group channel information measuring unit to form,
using the channel information associated with the one or more
subbands, group-based channel information of each subband
corresponding to the subband grouping information; and a
transmitting unit to transmit the group-based channel information
of each subband corresponding to the subband group to the BS
through a control channel.
20. The UE as claimed in claim 19, wherein the subband group
comprises one or more subbands included in a first component
carrier (CC) and one or more subbands included in a second CC; and
the channel information corresponds to information indicating a
status of a downlink (DL) channel of the subbands included in the
subband group.
21. The UE as claimed in claim 20, wherein at least one of the
first CC and the second CC does not include the control
channel.
22. The UE as claimed in claim 20, wherein the control channel
corresponds to a physical downlink control channel (PUCCH).
23. The UE as claimed in claim 19, wherein the channel information
includes at least one of channel quality indicator (C01)
information, a precoding matrix indicator (PMI), a rank indicator
(RI), information indicating a degree of noise of a channel,
information associated with an error occurring in a channel,
channel status information, and information associated with
measured quality of a channel.
24. The UE as claimed in claim 19, further comprising: an update
parameter extracting unit to extract a parameter to be used for
updating a subband group, based on the channel information measured
by the subband channel information measuring unit and the subband
group-based channel information measured by the subband group
channel information measuring unit, wherein the transmitting unit
generates subband group updating request information when the
parameter exceeds a tolerance, so as to transmit the subband group
updating request information to the BS; and wherein the subband
group updating request information comprises a portion
corresponding to a generation code or a cancellation code
indicating that a subband group is newly generated or cancelled, a
portion indicating a total number of newly generated subband groups
or cancelled subband groups, and a portion indicating
identification information (number) to be used for identifying each
generated or cancelled subband group and a subband included in each
subband group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the National Stage Entry of
International Application PCT/KR2010/008685, filed on Dec. 7, 2010,
and claims priority from and the benefit of Korean Patent
Application No. 10-2009-0124441, filed on Dec. 15, 2009, and Korean
Patent Application No. 10-2010-0123233, filed on Dec. 6, 2010, all
of which are incorporated herein by reference for all purposes as
if fully set forth herein.
BACKGROUND
[0002] 1. Field
[0003] The present invention relates to a wireless communication
system, and more particularly, to a method of transmitting and
receiving channel information through carrier aggregation, and a
user equipment (UE) and a base station (Bs) using the same.
[0004] 2. Discussion of the Background
[0005] As a bandwidth that a wireless communication system
including a user equipment (UE) and a base station (BS) is able to
use has increased or a plurality of component carriers (CCs) has
been utilized, channel information that needs to be reported by the
UE to the BS through a uplink (UL) so as to enable the BS to
recognize a channel status of a downlink (DL), has also
increased.
[0006] Accordingly, there is a desire for a method of effectively
transmitting channel information that needs to be reported by the
UE to the BS through the UL.
SUMMARY
[0007] An aspect of the present invention is to provide a method of
transmitting and receiving channel information through carrier
aggregation, and a user equipment (UE) and a base station (BS)
using the same.
[0008] Another aspect of the present invention is to provide a
method of transmitting and receiving channel information by forming
a group with respect to subbands including at least one CC, and a
UE and a BS using the same.
[0009] Another aspect of the present invention is to provide a
method of requesting group updating and performing group updating
with respect to at least one subband, and a UE and a BS using the
same.
[0010] Another aspect of the present invention is to provide a
method of transmitting and receiving channel information that
secures a backward compatibility when channel information is
transmitted through carrier aggregation, and a UE and a BS is using
the same.
[0011] Another aspect of the present invention is to provide a
method of effectively transmitting and receiving channel
information by simplifying a control channel when channel
information is transmitted through carrier aggregation.
[0012] In accordance with an aspect of the present invention, there
is provided a method for a base station (BS) to receive channel
information in a wireless communication system using at least one
component carrier (CC), the method including: receiving channel
information from a user equipment (UE), generating a subband group
with respect to one or more subbands included in the at least one
CC, based on the received channel information, transmitting
information associated with the generated subband group to the UE,
and receiving, from the UE through a control channel, group-based
channel information of each subband corresponding to the subband
group, and the subband group includes at least one subband having
the same channel information, and the information associated with
the subband group includes a total number of generated subband
groups, subband group identification information to be used for
identifying each subband group, and subband identification
information to be used for identifying a subband included in each
subband group.
[0013] In accordance with another aspect of the present invention,
there is provided a method for a UE to transmit channel information
in a wireless communication system that uses at least one CC, the
method including: transmitting, to a BS, channel information
associated with one or more subbands included in the at least one
CC, receiving, from the BS, information associated with a subband
group generated by grouping the one or more subbands included in
the at least one CC, transmitting, to the BS through a control
channel, group-based channel information of each subband by using
the channel information associated with the one or more subbands as
the group-based channel information of each subband corresponding
to the subband group, and the subband group includes at least one
subband having the same channel information, and the information
associated with the subband group includes a total number of
generated subband groups, subband group identification information
to be used for identifying each subband group, and subband
identification information used for identifying a subband included
in each subband group.
[0014] In accordance with another aspect of the present invention,
there is provided a wireless communication system, the system
including: a subband grouping management unit to generate a subband
group with respect to one or more subbands included in at least one
CC, based on channel information received from a UE, and a
transceiving unit to transmit subband grouping information
associated with the subband group to the UE, and to receive
group-based channel information of each subband corresponding to
the subband group through a control channel, and the subband group
includes at least one subband having the same channel information,
and the information associated with the subband group includes a
total number of generated subband groups, subband group
identification information to be used for identifying each subband
group, and subband identification information to be used for
identifying a subband included in each subband group.
[0015] In accordance with another aspect of the present invention,
there is provided a UE, the UE including: a receiving unit to
receive, from a BS, subband grouping information associated with a
subband group generated by grouping one or is more subbands
included in at least one CC, a subband channel information
measuring unit to measure channel information associated with the
one or more subbands included in the at least one CC, a subband
group channel information measuring unit to form, using the channel
information associated with the one or more subbands, group-based
channel information of each subband corresponding to the subband
grouping information, and a transmitting unit to transmit the
group-based channel information of each subband corresponding to
the subband group to the BS through a control channel.
[0016] As described in the foregoing, embodiments of the present
invention may provide a backward compatibility when channel
information is transmitted through carrier aggregation.
[0017] According to embodiments of the present invention, channel
information may be transmitted for each subband group through
subband grouping when the channel information is transmitted
through carrier aggregation and thus, a control channel may be
simplified and an amount of resources required for transmission may
be significantly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a block diagram illustrating a wireless
communication system according to an embodiment of the present
invention;
[0019] FIG. 2 is a diagram illustrating channel transmission
architecture in a wireless communication system that uses multiple
component carriers (CCs) according to an embodiment of the present
invention;
[0020] FIG. 3 is a diagram illustrating subband grouping according
to an is embodiment of the present invention;
[0021] FIG. 4 is a diagram illustrating an example of grouping
subbands having the same level according to an embodiment of the
present invention;
[0022] FIG. 5 is a flowchart illustrating a process where a base
station (BS) receives channel information of grouped subbands
according to an embodiment of the present invention;
[0023] FIG. 6 is a flowchart illustrating a process where a user
equipment (UE) transmits channel information of grouped subbands
according to an embodiment of the present invention;
[0024] FIG. 7 is a diagram illustrating a transmission architecture
for subband group information according to an embodiment of the
present invention;
[0025] FIG. 8 is a diagram illustrating a transmission architecture
for a subband group updating request according to an embodiment of
the present invention;
[0026] FIG. 9 is a diagram illustrating a configuration of a BS
that transmits information associated with grouped subbands
according to an embodiment of the present invention; and
[0027] FIG. 10 is a diagram illustrating a configuration of a UE
that transmits channel information of grouped subbands according to
an embodiment of the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0028] Hereinafter, exemplary embodiments of the present invention
will be described with reference to the accompanying drawings. In
the following description, the is same elements will be designated
by the same reference numerals although they are shown in different
drawings. Further, in the following description of the present
invention, a detailed description of known functions and
configurations incorporated herein will be omitted when it may make
the subject matter of the present invention rather unclear.
[0029] In addition, terms, such as first, second, A, B, (a), (b) or
the like may be used herein when describing components of the
present invention. Each of these terminologies is not used to
define an essence, order or sequence of a corresponding component
but used merely to distinguish the corresponding component from
other component(s). It should be noted that if it is described in
the specification that one component is "connected," "coupled" or
"joined" to another component, a third component may be
"connected," "coupled," and "joined" between the first and second
components, although the first component may be directly connected,
coupled or joined to the second component.
[0030] FIG. 1 illustrates a wireless communication system 100 to
transmit channel information according to an embodiment of the
present invention.
[0031] FIG. 1 is a block diagram illustrating a wireless
communication system according to an embodiment of the present
invention. The wireless communication system is a system to provide
various communication services such as voice data, packet data, and
the like.
[0032] Referring to FIG. 1, the wireless communication system may
include a user equipment (UE) 10 and a base station (BS) 20.
[0033] Throughout the specifications, the UE 10 may be an inclusive
concept is indicating a user terminal utilized in wireless
communication, including a UE in WCDMA, LTE, HSPA, and the like,
and a mobile station (MS), a user terminal (UT), a subscriber
station (SS), a wireless device, and the like in GSM.
[0034] In general, the BE 20 or a cell may refer to a fixed station
where communication with the UE 10 is performed, and may also be
referred to as a Node-B, an evolved Node-B (eNB), a base
transceiver system (BTS), an access point, and the like.
[0035] The BS 20 or the cell may be construed as an inclusive
concept indicating a portion of an area covered by a base station
(BS) in CDMA, a Node-B in WCDMA, and the like, and the concept may
include various coverage areas, such as a megacell, macrocell, a
microcell, a picocell, a femtocell, and the like.
[0036] The UE 10 and the BS 20 may be used as two inclusive
transceiving subjects to embody the technology and technical
concepts described in the specifications, and may not be limited to
a predetermined term or word. Here, an uplink (UL) refers to a
scheme of transmitting and receiving data from the UE 10 to the BS
20, and a downlink (DL) refers to a scheme of transmitting and
receiving data from the BS 20 to the UE 10.
[0037] Hereinafter, a multiple access scheme applied to the
wireless communication system is not limited. The wireless
communication system may utilize varied multiple access schemes,
such as Code Division Multiple Access (CDMA), Time Division
Multiple Access (TDMA), Frequency Division Multiple Access (FDMA),
Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA,
OFDM-TDMA, OFDM-CDMA, and the like.
[0038] UL transmission and DL transmission may be performed based
on a time division duplex (TDD) scheme that performs transmission
based on different times, or is based on a frequency division
duplex (FDD) scheme that performs transmission based on different
frequencies.
[0039] An embodiment of the present invention may be applicable to
resource allocation in an asynchronous wireless communication
scheme that is advanced through GSM, WCDMA, and HSPA, to be LTE and
LTE-advanced, and may be applicable to resource allocation in a
synchronous wireless communication scheme that is advanced through
CDMA and CDMA-2000, to be UMB. Embodiments of the present invention
may not be limited to a specific wireless communication scheme, and
may be applicable to all technical fields to which a technical idea
of the present invention is applicable.
[0040] Hereinafter, a channel information transmitting method of
reducing an amount of channel information increased due to use of
at least one component carrier (CC) will be described.
[0041] In the wireless communication system that provides the
channel information transmitting method, at least one CC may be
used, the UE 10 measures channel information for each subband
associated with each CC, and the UE 10 may transmit, to the BS 20,
subband group-based channel information that is generated based on
the channel information measured for each subband.
[0042] That is, the channel information may be transmitted for each
subband group (subband group-based channel information), as opposed
to being transmitted for each subband (subband-based channel
information) and thus, an amount of UL resources required for
reporting by the UE 10 to the BS 20 through a UL may be
significantly reduced.
[0043] Referring to FIG. 1, in the wireless communication system
that uses one or more CCs, each UE 10 may measure subband-based
channel information associated with each CC. Also, the UE 10 may
transmit, to the BS through a control channel, subband group-based
channel information for each subband group generated by grouping
one or more subbands associated with one or more CCs, based on the
measured channel information for each subband. That is, embodiments
of the present invention will describe a configuration and a
process of transmitting subband group-based channel information by
grouping a plurality of subbands included in a single CC, or by
grouping a plurality of subbands included in one or more CCs.
[0044] In embodiments of the present invention, the control channel
may be, for example, a physical uplink control channel (PUCCH) in
3GPP LTE/LTE-A.
[0045] The channel information measured for each subband described
in the forgoing may include, for example, at least one of a channel
quality indicator (CQI), precoding matrix indicators (PMI), a rank
indicator (RI), a signal-to-noise ratio (SNR), a frame error rate
(FER), and the like. Embodiments of the present invention may not
be limited to the examples of the channel information, and, as the
embodiments of the present invention are embodied, the channel
information may include various information used for measuring
various characteristics and qualities of a channel or for providing
measured results, for example, information indicating a degree of
noise of a channel, information associated with an error occurring
in a channel, channel status information, information associated
with measured quality of a channel, indication information thereof
(indicator), and the like.
[0046] In the wireless communication system that uses one or more
CCs, the BS 20 may receive, from the UE 10, subband-based channel
information associated with each CC, may generate a subband group
by grouping subbands based on the subband-based channel information
associated with each CC, may transmit subband grouping information
to the UE 10, and may receive subband group-based channel
information from the UE 10.
[0047] Here, "subband grouping" performed by the BS 20 based on
"subband-based channel information associated with each CC"
received from the UE 10 may correspond to inter-carrier subband
grouping that performs subband grouping by connecting subbands in
different CCs, intra-carrier subband grouping that performs subband
grouping by connecting subbands in the same CC, or subband grouping
that performs subband grouping based on both the inter-carrier
subband grouping and the intra-carrier subband grouping.
[0048] That is, embodiments of the present invention may group a
plurality of subbands into a single subband group, and the
plurality of subbands may be included in i) a single CC
(intra-carrier), may be included in ii) multiple CCs
(inter-carrier), or may be grouped based on iii) the combination of
the two schemes (intra-carrier and inter-carrier). In a case of ii)
or a case of iii), channel information of multiple carriers may be
transmitted.
[0049] The "subband grouping information" obtained by the subband
grouping as described in the foregoing may include, for example, at
least one of a total number of generated subband groups, subband
group identification information to be used for identifying each
subband group, subband identification information to be used for
identifying a subband included in each subband group, and the
like.
[0050] The UE 10 may extract a parameter to be used for updating a
subband group, based on subband-based channel information and
subband group-based channel information associated with each CC,
may generate subband group updating request information when the
parameter exceeds a tolerance, and may transmit the subband group
updating request information to the BS 20. According to an
embodiment of the present invention, the parameter may be computed
based on a difference between the subband group-based channel
information and the subband-based channel information of a
corresponding group.
[0051] The "subband group updating request information" transmitted
by the UE 10 to the BS 20 may include at least one of information
associated with a validity of entire subband grouping, information
associated with a list of subband groups that exceed a tolerance,
and information associated with an excess over a tolerance for each
subband group included in the list of the subband groups.
[0052] When the BS 20 receives the subband group updating request
information from the UE 10, the BS 20 may determine whether to
perform partial subband grouping or global subband grouping based
on the received subband group updating request information, and may
perform either the partial subband grouping or the global subband
grouping.
[0053] To achieve the above described channel information
transmission, the UE 10 may include a subband-based channel
information measuring unit to measure subband-based channel
information associated with each CC, a subband group-based channel
information calculator to receive subband grouping information from
the BS 20 based on the measured subband-based channel information
associated with each CC, to calculate subband group-based channel
information based on the subband grouping information, and to
transmit the subband group-based channel information to the BS 20,
a subband group updating management unit to extract a parameter to
be used for updating a subband group, based on the subband-based
channel information associated with each measured CC and the
calculated subband group-based channel information, to determine
whether the extracted parameter is less than or equal to a
tolerance, and to generate subband group updating request
information when the extracted parameter is greater than the
tolerance so as to transmit the subband group updating request
information to the BS 20, and the like.
[0054] To achieve the above described channel information
transmission, the BS 20 may include a subband grouping management
unit to classify subbands based on subband-based channel
information associated with each CC, received from the UE 10, to
generate a subband group by grouping the subbands based on a result
of the classification, and to transmit, to the UE 10, subband
grouping information associated with the subband grouping, a
subband group-based channel information receiving unit to receive
subband-group based channel information associated with the subband
grouping information from the UE 10, and the like.
[0055] The wireless communication system including the UE 10 and
the BS 20 may be applied to LTE-A which defines multiple-carriers
aggregation. Hereinafter, a channel information transmitting method
according to another embodiment of the present invention applied to
LTE-A will be described with reference to FIGS. 2 through 8.
[0056] In LTE, a standard may be developed by forming a UL and a DL
based on a single CC or a pair of CCs. The UL and the DL may
transmit control information through a control channel, such as a
physical downlink control channel (PDCCH), a physical control
format indicator channel (PCFICH), a physical hybrid ARQ indicator
channel (PHICH), a physical uplink control channel (PUCCH), and the
like, and may be configured as a data channel, such as a physical
downlink shared channel (PDSCH), a physical uplink shared channel
(PUSCH), and the like, so as to transmit data.
[0057] The data channel may be configured based on a resource block
(RB), and the RB may be configured in two dimensions of a time and
a frequency. Control information associated with allocation of
resources for each user and for each service may be transmitted and
managed by a control channel that is determined by an upper layer
of a physical layer of a service eNB
[0058] LTE-A uses a standard based on a single CC as a base (unit)
and has discussed coupling of a few bands having a bandwidth of 20
megahertz (MHz) or less, whereas LTE-A has discussed a band of a CC
having a bandwidth of 20 megahertz (MHz) or more.
[0059] LTE-A has discussed a multiple-carrier aggregation by taking
backward compatibility into consideration based on the base
standard of LTE. In a UL and a DL, five or more CCs are taken into
consideration. The important issue in the discussion of the carrier
aggregation may be how to extend a control channel and how to form
a data channel, as a number of CCs increases.
[0060] In the UL and the DL, one or more CCs or a pair of CCs may
be referred to as an anchor carrier, a primary cell, a serving
cell, or a special cell, and there may exist a CC that may access
the UE 10 in an initial stage and may receive security and
authentication information, and may be controlled with respect to a
multiple-carrier aggregation.
[0061] With respect to the carrier aggregation, UL
acknowledgement/negative acknowledgement (ACK/NACK) transmission
and DL channel information transmission including a CQI, a PMI, and
an RI are to be taken into consideration among various pieces of
information associated with designing of a control channel. The
CQI/PMI/RI information may be transmitted based on various schemes
through a PUCCH and a PUSCH which are UL control channels.
[0062] In a case of the CQI, as an example of channel status
information transmitted through the UL, CQI information may be
transmitted by periodic CQI reporting or aperiodic CQI reporting.
In the aperiodic CQI reporting, the CQI may be transmitted through
a PUSCH to which a UL resource is allocated by the BS 20, and the
CQI information may be reported by distinguishing a feedback
associated with a total band, a feedback associated with a subband
formed by the BS 20, and a feedback associated with a subband set
by the UE 10. A size of a subband may be determined based on a size
of a system band of an LTE system. When the periodic CQI reporting
is performed through a PUCCH, feedback reporting associated with a
subband formed by the BS 20 from among the three feedback schemes
of the PUSCH may not be supported.
[0063] For example, transmission of the CQI information through the
PUCCH may be used for transmitting information of 4 through 13 bits
in a 2/2a/2b form, and the CQI may be reported in an appropriate
form based on whether an MIMO scheme is used, a degree of a rank, a
length of a CP of a system, and the like.
[0064] Embodiments of the present invention may not be limited to
the examples of the channel information or the channel status
information, and, as the embodiments of the present invention are
embodied, the channel information may include various channel
status information, for example, various information used for
measuring characteristics and quality of a channel or providing
measured results.
[0065] In a channel information transmitting method according to an
embodiment of the present invention, it is assumed that M DL CCs
exist with respect to a DL and N UL CCs exist with respect to a UL.
A CC may refer to a CC included in a plurality of CCs used by the
wireless communication system.
[0066] Referring to FIG. 2, each DL CC may include a data channel
such as a PDSCH. However, each DL CC may or may not include a
control channel such as a PDCCH. That is, all the DL CCs may
include control channels, or a few of the DL CCs may include
control channels such as a PDCCH.
[0067] Each UL CC may include a data channel such as a PUSCH. Each
UL CC may or may not include a control channel. That is, all the UL
CCs may include control channels, or a few of the DL CCs may
include control channels such as a PUCCH.
[0068] That is, a few of all the DL CCs may selectively include
control channels such as a PDCCH. Also, a few of the UL CCs may
selectively select control channels such as a PUCCH.
[0069] In the channel information transmitting method according to
an embodiment of the present invention, a "subband group" may be
formed by connecting subbands based on an intra-carrier scheme and
an inter-carrier scheme. Here, a subband (SB) is a unit for UL
reporting.
[0070] FIG. 3 illustrates subband grouping according to an
embodiment of the present invention.
[0071] Referring to FIG. 3, a subband 1-1 (SB 1-1) in a DL CC #1, a
subband 2-1 (SB 2-1) and a subband 2-2 (SB 2-2) in a DL CC #2, and
a subband M-1 (SB M-1) in a DL #M may form the same subband group.
Also, a subband 2-3 (SB 2-3) in the DL CC #2 may be a subband that
is not grouped with another DL CC.
[0072] A subband group defined in an embodiment of the present
invention may generally include a definition of a subband that is a
unit of channel information transmitted in a UL, such as CQI/PMI/RI
information, defined in LTE/LTE-A.
[0073] Embodiments of the present invention may not be limited to
the examples of the channel information, and, as the embodiments of
the present invention are embodied, the channel information may
include various information used for measuring characteristics and
qualities of a channel or for providing measured results. That is,
a subband group may refer to an object that may be represented by
or reported as a predetermined channel information value.
[0074] A subband that is not grouped within a CC may exist, and the
subband may be regarded as a subband group of which a number of
subbands included in the group is one. A number of subbands of each
CC of carrier aggregation may be the same for each carrier
aggregation or may be different from one another. It is because a
characteristic of a channel of each CC may be changed for each UE
10, and subband grouping may not need to uniformly collect subbands
for each CC. Also, a single CC of to a subband group may be defined
to be a subband.
[0075] A rule of subband grouping that groups subbands into a group
may be as follows.
[0076] Subbands may be distinguished based on subbands that have
reported in an UL for each CC or for each intra-CC. Subbands may be
distinguished as a subband of which a channel status is in a
semi-static status and a subband of which a channel status is
relatively rapidly changed over time. Also, in each case, channels
may be distinguished as a channel having a relatively high SNR and
a channel having a relatively low SNR. Subband grouping may be
performed with respect to subbands having stable and similar SNR
levels, and may be performed with respect to subbands having
unstable and similar SNR levels.
[0077] FIG. 4 illustrates an example of grouping subbands having
the same level according to an embodiment of the present
invention.
[0078] Referring to FIG. 4, two CCs represented by a DL CC #1 and a
DL CC #2 are used. The DL CC #1 may include ten subbands
represented by 0 through 9, and the DL CC #2 may include five
subbands represented by 0 through 4.
[0079] The BS 20 may receive subband-based channel information, for
example, an SNR level, of the DL CC #1 and the DL CC #2 fed back or
reported by the UE 10, and may group subbands having the same SNR
level into a subband group as illustrated in FIG. 4.
[0080] For example, the subband 9 of the DL CC #1 and the subband 0
of the DL CC #2 have the same SNR level of "1" and thus, the
subband 9 and the subband 0, which are subbands of different CCs,
may be grouped into the same subband group.
[0081] As another example, the subband 3 and the subband 6 of the
CC #1 may have the same SNR level of "3" and thus, the subband 3
and the subband 6, which are subbands of the same CC, may be
grouped into the same subband group. Although not illustrated in
FIG. 4, the subband 3 and the subband 6 of the CC #1, and the
subband 3 of the DL CC #2 have the same SNR level of "3" and thus,
subbands of the same CC in is combination with a subband of
different CC may be grouped into a single subband group.
[0082] In this example, a subband that is not included in a subband
group, such as a subband 8 of the CC #1, may exist.
[0083] Hereinafter, operations of the BS 20 and the UE 10 for
transmission of channel information according to another embodiment
of the present invention will be described with reference to FIGS.
5 and 6.
[0084] FIG. 5 illustrates a process where a BS receives channel
information of grouped subbands according to an embodiment of the
present invention.
[0085] Referring to FIG. 5, in an initial operation, the BS 20 may
receive, from the UE 10, subband-based channel information
associated with each CC measured by the UE 10 (step S500).
[0086] Subsequently, the BS 20 may classify subbands for each CC,
based on the received subband-based channel information associated
with each CC (step S502).
[0087] Based on a result of the classification, subband grouping
may be determined (step S5404). The determined subband group may be
included in i) a single CC (intra-carrier), may be included in ii)
multiple CCs (inter-carrier), or may be based on iii) the
combination of the two schemes (intra-carrier and
inter-carrier).
[0088] The subband grouping may determine, for each UE 10, a
subband group that may reduce a load of transmission of UL control
information and may have low deterioration in a DL capacity. This
may not need to be performed for the entire band of the UE 10 and
may need to be performed for a predetermined band. The
configuration of a subband group may be transferred to the UE 10 in
a DL in a form of subband grouping information (referred to as
"control information A"). The subband grouping information, is also
referred to as control information A, may be configured as
information associated with a subband group formed by grouping
subbands having similar characteristics for each CC or information
associated with a subband group formed by grouping at least one
subband having a similar characteristic included in at least one
CC.
[0089] The subband grouping information associated with the
determined subband grouping may be transmitted to the UE 10 (step
S506). After the subband grouping information is transmitted to the
UE 10, the subband group-based channel information associated with
the subband grouping information may be received from the UE (step
S508). In this example, for a subband that does not form a subband
group, subband-based channel information may be received from the
UE 10 in the same manner as before.
[0090] When subband group updating request information is received
from the UE 10, whether to perform subband group updating may be
determined and partial or global subband group updating may be
performed by performing the steps from step 502.
[0091] In particular, the BS 20 may determine a subband group that
has a difference in channel information, for example, CQI/PMI/RI
information and the like, based on the subband group updating
request information, and may determine whether to partially update
subband grouping or to globally update subband grouping to be the
same as an initialization status, based on the subband group
updating request information. Therefore, the subband grouping
information may be updated, and the subband grouping information in
a form of the control A may be reported to the UE 10.
[0092] Embodiments of the present invention may not be limited to
the examples of the channel information and the channel status
information, and, as the embodiments of the present invention are
embodied, the channel information may include various channel
status information such as various information used for measuring
characteristics and qualities or for providing measured results.
That is, a subband group may refer to an object that may be
represented by or reported as a predetermined channel information
value. According to an embodiment of the present invention, a BS
may be configured to perform the process of FIG. 5.
[0093] FIG. 6 illustrates a process where a UE transmits channel
information of grouped subbands according to an embodiment of the
present invention.
[0094] Referring to FIG. 6, in an initial status before performing
subband grouping, the UE 10 may measure subband-based channel
information associated with each CC, for example, CQI/PMI/RI
information (step S600). Subsequently, the UE 10 may transmit, to
the BS 20, the measured subband-based channel information
associated with each CC (S602). From the initial status, subband
grouping may start based on a predetermined rule, previous access
records of the UE 10, information received from another BS,
information collected from another UE 10, information associated
with an initial ramping process of the UE 10, and the like. In this
example, an operation of the BS 20 with respect to the UE 10 may be
performed from a subband determining block.
[0095] Subsequently, the UE 10 may determine whether subband
grouping information is received from the BS 20 (step S604), may
calculate subband group-based channel information based on the
received subband grouping information (step S606) when the subband
grouping information is received, and may transmit the calculated
subband group-based channel information to the BS 20 (step S608).
The received subband group may be included in i) a single CC
(intra-carrier), may be included in ii) multiple CCs
(inter-carrier), or may be grouped based on iii) the combination of
the two schemes (intra-carrier and inter-carrier).
[0096] The UE 10 may transmit subband group-based channel
information based on a newly formed subband group through use of
the subband grouping information, instead of transmitting the
initial subband-based channel information associated with each CC,
for example, CQI/PMI/RI information. Embodiments of the present
invention may not be limited to the examples of the channel
information, and, as the embodiment of the present invention are
embodied, the channel information may include various channel
status information, for example, various information used for
measuring characteristics and qualities or for providing measured
results. That is, a subband group may refer to an object that may
be represented by or reported as a predetermined channel
information value.
[0097] The UE 10 may compare the subband group-based channel
information calculated in step S606 with the subband-based channel
information associated with each CC measured in step S600, and may
extract a parameter to be used for updating a subband group (step
S610). Here, the extracted parameter may be one of the
subband-based channel information associated with each CC measured
in step S600.
[0098] For example, although the subband group-based channel
information, for example, CQI/PMI/RI information, is transmitted,
the subband-based channel information, for example, CQI/PMI/RI
information, may be measured for each CC with respect to a formed
subband group. A difference between the two pieces of information
may be checked by comparing the measured subband-based channel
information and the subband group-based channel information
(CQI/PMI/RI information), and whether to perform subband group
updating may be determined based on a result of the checking and
the BS 20 may be informed about the determination.
[0099] The UE 10 may compare the extracted parameter and a
tolerance (step S612), may determine that a previously generated
subband group does not match a current channel status when the
parameter exceeds the tolerance, and may transmit group updating
request information to the BS 20 (step S614).
[0100] For example, when the difference between the two pieces of
information exceeds a predetermined threshold, that is, the
tolerance, this may be reported to the BS 20 through use of subband
group updating request information (referred to as control
information B). The subband group updating request information may
also be determined based on an FER value that is calculated based
on ACK/NACK information that may be detected from a DL data channel
associated with a subband group, in addition to CQI/PMI/RI. In
addition, the channel information may also include various channel
status information, for example, various information used for
measuring characteristics and qualities or for providing measured
results. That is, a subband group may refer to an object that may
be represented by or reported as a predetermined channel
information value.
[0101] The subband group updating request information may be
configured as information merely indicating a validity of a subband
group or information indicating a subband of a subband group that
has a difference in channel information, for example, a CQI/PMI/RI
and the like, and a degree of the difference.
[0102] However, when the parameter is less than or equal to the
tolerance, the UE 10 may determine that the previously generated
subband group matches the current is channel status, may
continuously perform steps from step S606 so as to transmit subband
group-based channel information to a BS. According to an embodiment
of the present invention, a UE may be configured to perform the
process of FIG. 6.
[0103] The subband grouping information in the form of the control
A and the subband group updating request information in the form of
the control B may be configured, for example, as illustrated in
FIGS. 7 and 8. FIG. 7 illustrates a transmission architecture for
subband group information according to an embodiment of the present
invention.
[0104] Referring to FIG. 7, subband grouping information in a form
of control information A may be configured to be (a) or (b) of FIG.
7, based on whether the subband group is newly generated or
cancelled.
[0105] Referring to (a) of FIG. 7, the subband grouping information
corresponding to a case where a subband group is newly generated,
may be configured to include a portion corresponding to a
generation code indicating that a subband group is newly generated,
a portion indicating a total number of newly generated subband
groups, and a portion indicating identification information
(number) to be used for identifying each subband group and a
subband included in each subband group.
[0106] Referring to (b) of FIG. 7, the subband grouping information
corresponding to a case where a subband group is cancelled, may be
configured to include a portion corresponding to a cancellation
code indicating that a subband group is cancelled and a portion
indicating identification information (number) to be used for
identifying a cancelled subband group and a subband included in the
cancelled subband group.
[0107] FIG. 8 illustrates a transmission architecture for a subband
group updating request according to an embodiment of the present
invention.
[0108] As illustrated in FIG. 8, subband group updating request
information in a form of control information B may be configured in
one of the types including a type (a) of FIG. 8 indicating a
validity of global subband grouping, a type (b) of FIG. 8
indicating a list of subband groups that have a problem in that a
parameter used for updating a subband group exceeds a tolerance,
and a type (c) of FIG. 8 indicating an excess of the parameter over
a tolerance along with the list of the subband groups having the
problem.
[0109] The subband grouping information in the form of control
information A and the subband group updating request information in
the form of control information B may be control information that
does not exist in the existing LTE standards and thus, there is a
desire for a new control channel to transfer the control
information. The control channel may need to be determined based on
upper layer signaling in an application where a subchannel group
updating is performed slowly, whereas a new channel, defined in a
corresponding physical layer, may need to be formed in an
application where updating is relatively promptly performed.
[0110] Referring again to FIGS. 5 and 6, operations of the BS 20
and the UE 10 that transmit channel information including
CQI/PMI/RI information and the like, to reported through an UL and
a DL, through subband grouping will be described as follows.
[0111] In an initial stage before performing subband grouping, the
UE 10 may transmit, to the BS 20, subband-based channel
information, for example, CQI/PMI/RI information (step S602).
[0112] The BS 20 may receive, from the UE 10, channel information
associated with each CC, for example, CQI/PMI/RI information, for
each subband, and may classify a channel characteristic of each
subband so as to perform subband grouping (steps S500, S502, and
S504). The BS 20 may transfer, to the UE 10, information associated
with configuration of a subband group in a form of subband grouping
information (referred to as "control information A"), and the UE 10
may receive the subband grouping information including the
configuration of the subband group (steps S506 and S604).
[0113] The UE 10 may transmit subband group-based channel
information based on the newly formed subband group based on the
subband grouping information, instead of transmitting subband-based
channel information associated with each CC, for example,
CQI/PMI/RI information (step S608).
[0114] Although the subband group-based channel information, for
example, CQI/PMI/RI information, is transmitted for each subband
group, subband-based channel information associated with each CC,
for example, CQI/PMI/RI information, may be measured with respect
to a formed subband group. A difference between the two pieces of
information may be checked by comparing the measured subband-based
channel information and the subband group-based channel information
(CQI/PMI/RI information), and whether to perform subband group
updating may be determined based on a result of the checking and
the BS 20 may be informed about the determination (steps S610,
S612, and S614). For example, when the difference between the two
pieces of information exceeds a predetermined threshold, that is, a
tolerance in step S612, subband group updating request information
(referred to as control information B) may be transmitted to the BS
20 in step S614.
[0115] The BS 20 may determine a subband group that has a
difference in channel information, for example, CQI/PMI/RI
information and the like, based on the subband group updating
request information, and may determine whether to partially update
subchannel grouping or globally update subchannel grouping to be
the same as an initialization status, based on the subband group
updating request information. Accordingly, the subband grouping
information may be updated, and the UE 10 may be informed about the
subband grouping information in the form of the control information
A (step S510).
[0116] The configurations of the BS 20 and the UE 10 to transmit
channel information, reported in a UL and a DL, through subband
grouping will be described as follows.
[0117] FIG. 9 illustrates a configuration of a BS that transmits
information associated with grouped subbands according to an
embodiment of the present invention.
[0118] Referring to FIG. 9, the BS may include a module to manage
subband grouping (subband grouping management unit 910), and a
transceiving unit 920 to perform transmission and reception of
information with a UE.
[0119] In particular, the subband grouping management unit 910 may
generate a subband group including subbands based on channel
information associated with the subbands, received from the UE. The
transceiving unit 920 may receive the channel information
associated with the subbands from the UE, may transmit, to the UE,
subband grouping information associated with the subband group, and
may receive channel information associated with the subband group
from the UE.
[0120] Here, a subband may be included in one or more CCs. A
subband group may include at least one subband having the same
channel information. Information associated with the subband group
may include at least one of a total number of generated subband
groups, subband group identification information to be used for
identifying each subband group, and subband identification
information to be used for identifying a subband included in each
subband group.
[0121] When the UE transmits subband group updating request
information separately and the transceiving unit 920 receives the
subband group updating request information, the subband grouping
management unit 910 may generate information associated with an
updated subband group, and the transceiving unit 920 may transmit
the information to the UE.
[0122] FIG. 10 illustrates a configuration of a UE that transmits
channel information of grouped subbands according to an
embodiment.
[0123] Referring to FIG. 10, the UE may include a receiving unit
1040 to receive subband grouping information associated with a
subband group generated by grouping one or more subbands included
in at least one CC, a subband channel information measuring unit
1010 to measure channel information associated with the one or more
subbands included in the at least one CC, a subband group channel
information measuring unit 1020 to form group-based channel
information of each subband corresponding to the subband grouping
information through use of the channel information associated with
the one or more subbands, and a transmitting unit 1050 to transmit,
to a BS through a control channel, the group-based channel
information of each subband corresponding to the subband group.
[0124] Here, the subband group channel information measuring unit
1020 that measures subband group-based channel information may be
configured as the same unit as the subband channel information
measuring unit 1010. In this example, the subband group channel
information measuring unit 1020 that provides a function of the
subband channel information measuring unit 1010 may measure channel
information associated with the one or more subbands included in
the at least one CC, and may form group-based channel information
of each subband corresponding to the subband grouping information.
Also, the subband group channel information measuring unit 1020 may
receive channel information associated with subbands measured by
the subband channel information measuring unit 1010, and may form
the subband group-based channel information.
[0125] In this example, the UE may further include an update
parameter extracting unit 130. The update parameter extracting unit
130 may extract a parameter to be used for updating a subband
group, based on the channel information measured by the subband
channel information measuring unit 1010 and the subband group-based
channel information measured by the subband group channel
information measuring unit 1020, and the transmitting unit may
generate subband group updating request information when the
parameter exceeds a predetermined tolerance so as to transmit the
subband group updating request information to the BS.
[0126] In FIGS. 9 and 10, the subband grouping information
("control information A" as described in FIG. 7) including
configuration of the subband group may be configured as information
associated with a subband group formed by grouping subbands having
similar characteristics for each CC, or as information associated
with a subband group formed by grouping at least one subband having
a similar characteristic included in at least one CC.
[0127] In a case where a subband group is generated as shown in (a)
of FIG. 7, the information associated with the subband group may
include at least one of a generation code indicating generation of
a subband group, a total number of generated subband groups,
subband group identification information to be use for identifying
each subband group, and a subband identification information
(number) to be used for identifying a subband included in each
subband group.
[0128] In a case where a subband group is cancelled as shown in (b)
of FIG. 7, the information associated with the subband group may
include at least one of a cancellation code indicating cancellation
of a subband group and a portion indicating identification
information (number) associated with a cancelled subband group and
a subband included in the cancelled subband group
[0129] In FIGS. 9 and 10, the subband group updating request
information ("control information B" as described in FIG. 8) may be
determined based on an FER value calculated based on ACK/NACK
information that may be detected from a DL data channel associated
with a subband group, in addition to CQI/PMI/RI. In addition, the
channel information may include various channel status information,
for example, information for measuring characteristics and
qualities or for providing a measured results.
[0130] That is, according to the embodiments of the present
invention, a subband group may refer to an object that may be
represented by or reported as a predetermined channel information
value. The subband group updating request information may be
embodied in a way that indicates a validity of subband grouping as
shown in (a) of FIG. 8, that indicates a list of subband groups
having a problem in that a parameter to be used for subband group
updating exceeds a tolerance as shown in (b) of FIG. 8, or that
transfers an excess of the parameter over the tolerance along with
the list of the subband group having the problem, as shown in (c)
of FIG. 8.
[0131] The subband group of FIGS. 9 and 10 may include i) subbands
of a single CC (intra-carrier), may include ii) subbands included
in multiple CCs (inter-carrier), or may be formed based on iii) the
combination of the two schemes (intra-carrier and
inter-carrier).
[0132] The control channel of FIGS. 9 and 10 may be, for example, a
PUCCH, and channel information may include at least one of CQI
information, a PMI, an RI, information indicating a degree of noise
of channel, information associated with an error occurring in a
channel, channel status information, and information associated
with a measured quality of a channel.
[0133] Although a preferred embodiment of the present invention has
been described for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying claims.
Therefore, the embodiments disclosed in the present invention are
intended to illustrate the scope of the technical idea of the
present invention, and the scope of the present invention is not
limited by the embodiment. The scope of the present invention shall
be construed on the basis of the accompanying claims in such a
manner that all of the technical ideas included within the scope
equivalent to the claims belong to the present invention.
* * * * *